If the plans call for the CG at 5.5" from the LE and you have it at 5, moving it farther forward isn't going to help. In fact, you should consider moving it back to the recommend point to start with.

Actually, this made me think a bit more. I suspect you'll snap less if you do, in fact, change engines down to the .46. I think the extra weight of the larger engine is driving up your wingloading, and that will always increase snapping tendancy. So loose some weight, and the snapping will reduce.